w w w e tr .X m eP UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Ordinary Level e ap .c rs om MARK SCHEME for the May/June 2011 question paper for the guidance of teachers 5070 CHEMISTRY 5070/21 Paper 2 (Theory)‚ maximum raw mark 75 This mark scheme is published as an aid to teachers and candidates‚ to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that
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Unit 1- Lesson 2 Chemistry Key Questions 4. Name Formula Cobalt (II) Nitrate Co(NO3)2 Calcium Phosphate Ca 3 (PO 4) 2 Disphosphorus trioxide P203 Ammonium Sulfate (NH 4) 2 (SO 4) Gold (III) hydroxide AuH3O3 Platinum (II) Oxide PtO Gallium carbonate
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SYNTHESIS AND CHEMISTRY OF K2S2O8 ABSTRACT In this experiment‚ a sample of K2S2O8 was prepared by the electrolysis of an aqueous solution of H2SO4 and K2SO4. The peroxodisulfate anion‚ S2O82-‚ was also observed for its ability to serve as a counterion for precipitation by preparing a copper (II) complex by reacting hydrated copper (II) sulfate with ammonium peroxodisulfate in the presence of pyridine. This same ability‚ coupled with its strong oxidizing ability allowed for stabilization of
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Radha Shukla Determination of the Empirical Formula of Silver Oxide Will/Radha College Chemistry 9/12 – 9/13 9/17 The purpose of this lab is to use one of the ways to identify different compounds and be able to tell them apart. Based off of experimentation‚ the empirical formula of the given silver oxide will be determined. Materials: Chemicals: Silver Oxide‚ 0.5g Equipment: Balance‚ 0.001-g or 0.0001-g precision Bunsen Burner Clay pipestem triangle Crucible and cubicle lid‚ 15-
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Ch. 1 Fundamentals of Chemistry Subchapter – Stoichiometry and Units 1. An element X forms an oxide with the formula X4O10. If 31 g of X combines with 40 g of oxygen‚ what is the identity of X? A. N B. P C. C D. S Correct Answer: B: P Explanation: We can solve for the atomic mass of X to identify it. The amount in g of X for any amount in g of O is given by: Rearranging the above equation and substituting the given mass of X and O‚ we get: Thus‚ the atomic mass of X
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Nerissa Govender 209539579 CHEM 310 Experiment 1- Synthesis of Co (acac)3 Date of experiment performed: 03 August 2011 Date of hand in: 10 August 2011 Aim To prepare cobalt (III) acetylacetonate in the laboratory using cobalt (II) carbonate and acetylacetone at room temperature and pressure. Introduction The anion acetylacetone (acac) used in this practical functions as a ligand which forms a complex with the cobalt metal cation in an octahedral array where there is electrostatic bonds
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Trees occupy an important place in the life of man. The trees provide us flowers‚ fruits‚ fodder for animals‚ wood for fire and furniture and provide cool shadow from scorching sun. They give us so many such good things and yet expect nothing in return. Trees give us fruits for food and flowers for pleasure. They provide us timber (wood) for building our houses and making furniture. They provide us wood for fuel. They supply sleepers for the railway line. Many trees provide us medicinal products
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Importance and Value of Trees Since the beginning‚ trees have furnished us with two of life’s essentials‚ food and oxygen. As we evolved‚ they provided additional necessities such as shelter‚ medicine‚ and tools. Today‚ their value continues to increase and more benefits of trees are being discovered as their role expands to satisfy the needs created by our modern lifestyles. Community and Social Value Trees are an important part of every community. Our streets‚ parks‚ playgrounds and backyards
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SK0013 PHYSICAL CHEMISTRY – TUTORIAL 2 MATTER II 1. Given the formula K2CO3‚ determine the percent composition (fraction of K‚ C and O) of potassium carbonate (K2CO3 = 138.205 g/mol). 2. A compound has the following composition: C=40%‚ H=6.67%‚ O=53.3%. Its molecular weight is 60.0. Derive its molecular weight. 3. Determine the molar concentration of each of the following solutions: a) 166 g KI per L solution b) 33.0 g (NH4)2SO4 in 200 mL solution c) 12.5 g CuSO4.5H2O in 100 mL solution
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COORDINATION COMPOUNDS: * FLEXIDENTATE CHARACTER OF POLYDENTATE LIGANDS; * Poly dentate ligands have flexi dentate character in the sense that all donors atoms may not form coordinate bonds with the central metal atom or ion. For example; EDTA which is the hexa dentate ligand also acts as tetra dentate or penta dentate in certain complexes. Similarly sulphate ion‚ which is a bi dentate ligand‚ also acts as a mono dentate ligand in certain complexes‚ e.g. in [Co(SO4)(NH3)5]Cl. * LABILE
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